Breast pump assemblies for extracting or expressing breast milk from a woman's breasts for later use to feed by an infant, have been available for years. Typically, these breast pump assemblies include a source of reduced pressure or vacuum, and at least one milking unit, which is includes a funnel-shaped hood, or breast shield, and a storage container. The breast shield is placed over the women's nipple and a substantial portion of the breast. A reduced pressure or vacuum is intermittently generated in the breast shield in a manner that causes milk to be expressed from the breast. The milk then typically flows to the storage container for later use. Although vacuum is what is typically employed in the operation of a breast pump assembly, positive pressure may also be conveyed in desired applications.
Generally, two types of breast pump assemblies have been marketed for use by nursing women: manually operated breast pump assemblies; and motor-driven breast pump assemblies. In manually operated breast pump assemblies, the intermittent vacuum is typically generated by means of a piston type pump. The piston pump generally includes a piston cylinder, which is connected to the breast shield, and a piston, slidably disposed within the piston cylinder. The piston has a hand-drivable piston rod connected thereto by which a person operating the breast pump assembly can manually move the piston back and forth within the piston cylinder, thus generating the vacuum. The intermittent vacuum in motor-driven breast pump assemblies is typically generated by a similar piston pump, but the piston pump is connected to an electrically powered motor drive unit, and the motor drive unit moves the piston back and forth within the piston cylinder. There is a breast pump assembly sold by Medela, Inc. under the mark LACTINA®, which has a motor drive unit adapted for operating a piston pump which could otherwise be used for a manually operated breast pump assembly. An example of this manual, yet also motorized breast pump assembly is disclosed in U.S. Pat. No. 5,007,899 (“the '899 patent”). The motor drive unit is separate from the breast shield. The vacuum generated when the motor drive unit moves the piston back and forth within the piston cylinder is transmitted to the breast shield through plastic tubing, which is connected to both the breast shield and the piston pump. The plastic tubing is often connected to the piston pump and/or the breast shield by use of an adapter. Because of the transfer of air throughout the breast pump assembly, the adapter must provide an airtight seal. Additionally, the user should be able to easily manipulate the adapter.
In the type of breast pump assembly disclosed in the '899 patent, where the breast shield can be used in a manual or a motorized mode, the breast shields and their pumps must be precisely matched in order to provide a safe and efficiently operating unit. The piston pumps used with the '899 patent breast pump assembly are, for example, precisely tuned to the operational function of the breast shield used therewith, as, for instance, concerning the volume of air moved in the cyclical action of the pump. Use of a different pump or breast shield can adversely affect the use of the subject breast pump assembly.
Accordingly, there is a demand for an adapter that provides a means for precisely matching breast shields and corresponding pumps. The present invention satisfies this demand.